Safety device for a projectile



14, 1956 H. H. DDDDDD ER 2,758,545

Y DEVICE FOR A PROJECTILE as ll gwunwvbom J7. fierin yer r mwzf 8. 14, 19 H. H. DERINGER 2,758,545

SAFETY DEVICE FOR A PROJECTILE Filed Nov. 15, 1945 2 Sheets-Sheet 2 E64. 23 I8 is I5 25 gjmcwtm 17. If. Dari n yer 4 WM MJZ United States Patent 2,758,545 SAFETY DEVICE FOR A PROJECTILE Harry H. Deringer United States Navy 'Chestert own, Md.

Application November 15, 1943, Serial No. 510,333 Claims. (Cl. 102-79) (Granted under Title 35, U. S. Code (1952), sec. 266) This invention relates to safety devices for a projectile adapted to be fired from a gun and provided with a firing pin adapted to strike a percussion cap with sufficient force to explode an explosive charge within the projectile as the projectile strikes the target, in which means are employed for preventing the premature firing of the explosive charge until the projectile has traveled a safe distance beyond the muzzle of the gun. More specifically the invention relates to a fuse for a projectile in which the firing pin is locked in a safe position with respect to the detonator until the projectile has attained a predetermined speed of rotation during the firing of the projectile from a gun and the force of acceleration of the projectile has diminished to a value corresponding to the force of acceleration acting on the projectile at a safe distance from the gun after the projectile has been fired therefrom.

In devices of this character heretofore devised for preventing the premature explosion of the projectile in or within the vicinity of the gun as the gun is fired, it has been the usual practice to employ a pair of cylindrical detents adapted to be moved outwardly within radially disposed tubular apertures disposed within the projectile and thereby remove a restraint from the firing pin and cause the projectile to be armed as the detents move radially outward by the centrifugal force acting thereon as the projectile is forced through the bore of the gun by the explosion of the main explosive charge. In the event that the detents should be moved to the unlocked position before the projectile has traveled beyond the muzzle of the gun, the force of acceleration acting on the movable firing member may cause the firing pin to strike the detonator with sufiicient force to explode the projectile while the projectile is still within the barrel of the gun thereby damaging or destroying the gun and causing casualties to the gun crew and other personnel within the vicinity of the gun.

In accordance with the present invention this difiiculty is overcome by employing a pair of locking detents in which the surfaces thereof comprise a pair of intersecting conic sections adapted to coact with complementary cam'surfaces of the fuse support sufliciently to prevent movement of the detents outwardly to an unlocking position as the gun is fired until the force of acceleration of the projectile has decreased sufiiciently to permit such movement.

One of the objects of the present invention is the provision of new and improved means for preventing the premature firing of an explosive charge within a projectile during the transportation, handling, loading and firing of the projectile from a gun.

Another of the objects is to provide a new and improved device for maintaining the firing pin of a projectile locked in a safe position as the projectile is fired from a gun until a predetermined relation between the acceleration of the projectile and the speed of rotation thereof about the axis of the projectile has been reached. Another object is to provide a new and improved device 2,758,545 Patented Aug. 14, 1956 for preventing the premature firing of an explosive charge within a projectile in which the firing pin is locked in a safe position until the velocity of the projectile has reached substantially the maximum value after being fired from the gun and in which the locking means are maintained in the locking position by the force of acceleration of the projectile during the travel of the projectile through the gun.

A further object is to provide a new and improved device for locking the firing pin of a projectile in a the projectile is shot clear of the gun which is economical to manufacture, reliable in operation, and which possesses all of the desired qualities of ruggedness and durability.

Still other objects and advantages will be apparent from the following description taken in connection with the accompanying drawings of which:

- Fig. l is a view in elevation and partially in section of a projectile employing the device of the present invention according to a preferred embodiment thereof;

Fig. 2 is a view somewhat enlarged and partially broken away taken substantially along the line 2-2 of Fig. 1;

Fig. 3 is anvenlarged view of the fuse locking mechanism and partially in section showing the locking detents maintained in the unlocked position by centrifugal force as the projectile travels alonga trajectory;

Fig. 4 is a view partially in section and partially broken away taken substantially along the line 44 of Fig. 3;

Fig. 5 is a greatly enlarged view in elevation of one of thei locking detents employed with the device of Fig. 1; an

Fig. 6 is a view in section and partially broken away of a locking detent and supporting means therefor in Fig. 1 thereof, there is shown thereon a projectile indicated generally by the numeral 10 having an annular recessed portion 11 therein adapted to be engaged by a andloading of the shell into a'gun, as is well known in the art to which-the present invention pertains. projectile is also preferably provided with an annular sleeve 12 of' material suitable for the purpose such, for example, as brass adapted to be engaged by the riding propelled outwardly therement imparted thereto by The projectile is also nose 13 composed of such, for example, as

the rifling of the gun.

provided with a leading end or material suitable for the purpose zinc and secured to the main body 14 of the projectile in any suitable manner as by threading the parts together. The nose is provided with a circular well 15 having the axis thereof arranged coaxially with the axis of the projectile to which is secured in any suitable manner a bearing member or support 16 having a shoulder 17 thereon adapted to engage a surface 18 formed within the nose of the projectile. Slidably disposed within the bearing member 16 is a firing pin 19 having an extending thereto.

pin rearwardly into engagement with a percussion cap or other suitable detonating device in response to the crushing of the nose of the projectile as the proi ct strikes the erg It w l ,,.o urs ..b und rstood that if desired the projecting member 21 may be made of the same material as the firing pin and, furthermore, the firing Pin and projecting member may be of integral con- S ruction.

The support 16 is providedwith, a pair-of diametrically arranged apertures 22 within which is respectively disposeda pair of locking detents 23 adapted. to be releasably maintained in engagement with a reduced cylindIical portion 24 of the firing pinv by a circular spring 25 encircling the detents and adapted to urgethe detents yieldably and inwardly against the firing pin, a chamber 26 being provided within the nose of'the projectile of. sufficicnt size to permit the spring 25. toexpand and thereby release. the detents from the locking position thereof, as il moreelcarlyfappear as the description proceeds.

The locking detents comprise twolintersecting-conic frustums 27 and a pair of cylindrical surfaces28, Fig.6, he-ends f the detents being preferably conic sect-ions whereby the pressure of the: spring 25. against eachof the detents is applied. along a line intersecting the axis of the detent. In, like manner the pressure of the detent against the cylindricalportion .24 of the firing pin is applied along a line intersecting theaxis of the detent. The detent is adapted to. be engaged. at the surface of. one of the conic frustums 27 by a shoulder 29 on the support 16 formed by an orifice within the support of sumcient sizetopermit sliding movement of the firing pin therethroughwhen the firing pin has been unlocked from .a. safe position by movement of the detents 23 from the. path oftravel of thefiring pin. With the detents in'tbe locking; position, Fig. 1, the firing pinis maintained locked in. a safe position andpreventcd from being brought. into contact with the detonator by reasonof theengagement. of a cylindrical portion 28 of each of the detents with the shoulder 31 on the firing pin. 1

As the projectile travels through the bore of the gun in response to thefiring of the gun, the. firing pin including the extending member 21 is urged toward therear of the projectile by the force of acceleration applied thereto by the shoulder 29 on the. support .16 and the detents aforesaid. This force resulting from the acceleration of theprojectile in response to the expansion'of the gases within the gun, is applied in a direction along; the path of travel of the projectile and is hereinafter referred to as a, setback force. This setback force decays rapidly as the projectile leaves the muzzle. of. the gun and attains zero value when the maximum velocity of the. projectile is. reached. It will bereadily understoodfromaninspection of the arrangement of the various-parts-of' Fig. '1

that the setback force of thefiringpin-appliedto the: detents. effectively prevents the outwardradialmovement of the detents from the initial locking positionzthereof-by reason of. the engagement of theconic'frustums orsections27 with the. shoulder 29 of the support 16.

As the projectile is propelled along-the bore-of the gun by the, explosivev blast, therifling ofthebore-engages the sleeve 12 and imparts rotative movement. to -the,pro-' jectile thereby causing the detents to-be .spun rapidly about the. axis of the-projectile and a centrifugal'forceto be generated thereby in accordance with the law of com trifugal, force applied to rotating masses. This-force, as is well known, is proportional tothe productof -the mass andythesquare of the velocity and inversely/pro. portional to. the. radius of curvature andmaybe eonveniently expressed by the formula This force is of :sufiicientttrength-toovercome tension in the spring 25. and to-cause thez-detcnts'tomova outwardly tofan unlocking or :armed position and-clear of the path of travel of the firing pin. The detents, how-- ever, are prevented from being moved outwardly 1110 unlocking position by the setbackforce applied thereto ,by the firing pin until the projectile has moved asafe distance beyond the muzzle of the gun, at which distance the setback force is reduced sufficiently for the centrifugal force of the detents to move the detents outwardly into the armed position thereby unlocking the firing pin and arming the projectile. As the detents move outwardly into the armed position, the firing pin is moved slightly forward with respect to the nose of the projectile by reason of the movement of the conic surfaces 27 of the detents against the shoulder 29 of the support 16.

As the gun is fired the initial movement of the projectile awayfrom the shell is a motion of translation and when the projectile has moved a predetermined distance within thebore of the gun, the sleeve 12 engages the rifling of the bore and rotation of the projectile is initiated thereby. From the foregoing, it will be apparent that the setback force is applied to the projectile prior to the rotative movement thereof and thus the detents are effectively lockedin the locking position thereof by the setback force before the centrifugal force comes into play, thereby providing an arrangement in which there is no possibility of prematurely'arming the, projectile until the projectile has safely cleared the gun and the setback force has decreased to, avalue insufficient to cause the firing pin to strike the dctonator and explode the projectile as the detents move into the unlocking or armed position.

0n Fig. 3 is shown the detents maintained in their unlocking or unarmed position by centrifugal force during the travel ofprojectile along a trajectory, the spring.25 being expanded into engagement with the cylindrical wall of the chamber 26. The projectile is thus armed when the; setback force of the firing pin 19 is insufiicient to overcome the centrifugal force of the locking members and the firing pin, therefore, is in readiness to be driven againstthedetonator by the force of impact received as the projectile strikes the target.

On Fig. 6 there isshown one of a pair of locking detents-32 and the supporting means therefor in accordance with an alternative form of the invention. The detent 32 is generally similar to the detent 23 and may, if desired, be used in thesame structure employed in connection with the detents 23. The detent 32, in the specific form illustrated, comprises a pair of cylindrical surfaces 33 in abutting relation with a pair of conic frustums 34, the conic frustums being connected by a cylindrical surface 35. The ends of the detent are preferably formed in a manner similar to the detent 23 and adapted to be engaged bythe spring 25 and the firing pin 19 at the reduced cylindrical portion. 24 thereof. The operation .-of the detents 32 is generallysimilar to the 'operationof the detents .23, the detents being yieldably maintained in thelockingposition by the spring 25 and bythesetback force of the firing pin 19 until the projectile has moved a safe distance beyond the muzzle of the gun at which time the setback forceis reduced sufficicntly topermit the detents to be moved radially outward by the centrifugal-force acting thereon and thereby arm the projectile.

Whilethe invention has been described with particularity in reference to two embodiments disclosed, it will be apparent to those skilled in the art to which the inven-. tion pertains, after understanding the invention, that the invention-in its broader aspectcould be carried ;out by other instrumentalities, and it is understood that the;terms used. in the claims are wordsv of description and. not of limitation except as necessitated by the prior art.

Iheinvention herein described andv claimed may be manufactured and used by or for the Government of the United States of Americafor governmental purposes withoutpaymentof any royalties thereon or therefor.

What is claimed asnew and desired to be secured-by Letters Patent. of the United States is:

I. A safety device for a projectile adapted toibe fired from-agar! and" having an e rplosi've charge therein, me ans including a firing pi'n slidably and coaxially arranged within said projectile and having a'stop 'member thereon,

a striker on the firing pin adjacent said stop member andadapted to fire said explosive charge, said strikerhaving a cylindrical portion thereon, a cylindrical bore disposed within the projectile with the axis thereof intersecting the axis of the striker, a pair of detents respectively arranged within said bore on opposite sides of said striker and adapted to be tilted within the bore and moved from an initial safe position to an armed position by centrifugal force during the travel of the projectile along a trajectory, each of said detents having a pair of abutting frustum portions adapted to impart a driving force to the firing pin as the detents move from said safe position to said armed position and a pair of cylindrical portions respectively intersecting the bases of the frustum portions and a pair of conical surfaces respectively arranged on the end portions thereof in intersecting relation with the cylindrical portions, means forming a circular chamber within the projectile in communication with the outer ends of said bore and having the axis thereof in alignment with said striker, a substantially cylindrical resilient member disposed within said chamber and adapted to urge the detents yieldably against the striker by pressure applied thereby, the conical surfaces on the ends of the detents being so proportioned as to apply said pressure along a line of contact between each of the detents and the resilient member and a second line of contact between each of the detents and the cylindrical portion of the striker when the detents are tilted within said bore, each of said lines of contacts being parallel to the striker, and means on the projectile arranged adjacent the striker and adapted to coact with the inner frustum portions of the detents for preventing outward movement of the detents by centrifugal force as the projectile is fired from the gun until the setback force of the firing pin has decreased sufficiently to permit the firing pin to be moved forwardly by the driving force imparted thereto by said frustum portions as the detents move outwardly to said armed position.

2. A safety device for a projectile adapted to be fired from a gun and having an explosive charge therein, means including a firing pin slidably and coaxially arranged within said projectile and having a stop member thereon, a striker on the firing pin adjacent said stop member and adapted to fire said explosive charge, said striker having a cylindrical portion thereon, a cylindrical bore disposed within the projectile with the axis thereof intersecting the axis of the striker, a pair of detents respectively arranged within said bore on opposite sides of said striker and adapted to be tilted for pivotal movement within the bore and moved from an initial safe position to an armed position by centrifugal force during the travel of the projectile along a trajectory, a pair of conical surfaces respectively arranged on the end portions of said detents, means forming a circular chamber Within the projectile in communication with the outer ends of said bore and having the axis thereof in alignment with said striker, an annular resilient member disposed within said chamber and adapted to urge the detents yieldably against the striker by pressure applied thereby, the conical surfaces on the ends of the detents being adapted to apply said pressure along a line of contact between each of the detents and the resilient member and a second line of contact between each of the detents and the cylindrical portion of the striker when the detents are tilted within said bore, each of said lines of contacts being parallel to the striker, and means arranged adjacent the striker for preventing outward movement of the detents by centrifugal force as the projectile is fired from thegun until the setback force of the firing pin has decreased sufficiently to permit pivotal movement of the detents to drive the firing pin forwardly.

3. A safety device for a projectile adapted to be fired from a gun and having an explosive charge therein, a firing pin slidably and coaxially arranged within said projectile, a stop member arranged on said firing pin, a striker con- 6 centrically formed on said stop lindrical portion thereon, a cylindrical bore disposed within the projectile, a pair of detents respectively arranged within said bores on opposite sides of said striker and adapted to be tilted within the bore and moved from an initial safe position to an armed position by centrif ugal force during the travel of the projectile along a trajectory, a pair of frustum portions on each of said detents adaptable to impart a driving force to'the firing pin as the detents move from said safe position to said armed position, a pair of cylindrical portions respectively intersecting the bases of the frustum portions, a pair of conical surfaces respectively arranged on the end portions of said detents in intersecting relation with the cylindrical portions thereof, means forming a circular chamber within the projectile, an annular resilient member disposed within said chamber and adapted to urge the detents yieldably against the striker by pressure applied thereby, said conical surfaces being so'proportioned as to apply said pressure along a line of contact between each of the detents and the resilient member and a second line of contact between each of the detents and the cylindrical portion of said striker when the detents are tilted within said bore, and means on the projectile adapted to coact with the inner frustum portion of each of the detents for preventing the detents from being moved to said armed position by said centrifugal force until the setback force of the firing pin has decreased sufiiciently to permit pin to be cammed forwardly by the driving force imparted by said frustum portions as the detents move outwardly to said armed position.

4. In a safety device for a projectile adapted to be fired from a gun and having an explosive charge arranged within said projectile, in combination, a support arranged within said projectile, a firing pin slidably arranged within said support and having a stop member thereon, a striker on the firing pin adjacent said stop member and adapted to fire said explosive charge upon impact of the projectile with a target, a cylindrical bore disposed within the support with the axis thereof intersecting the axis of the striker, a pair of detents respectively arranged within said bore on opposite sides of said striker, said detents being adapted to be tilted within the bore and moved from an initial safe position to an armed position by centrifugal force, each of said detents having a pair of abutting frustum portions thereon adaptable to impart a driving force to the firing pin as the detents move from said safe position to said armed position, a pair of cylindrical portions respectively intersecting the bases of the frustum portions and a pair of conical surfaces respectively arranged on the end portions thereof in intersecting relation with the cylindrical portions, means forming a circular chamber within the projectile in communication with the outer ends of said bore and having the axis thereof in alignment with said striker, an annular resilient member disposed within said chamber and adapted to urge the detents yieldably against the striker by pressure applied thereby, said conical surfaces on the ends of the detents being adapted to apply said pressure along a line of contact between each of the detents and the resilient member and a second line of contact between each of the detents and the striker when the detents are tilted within said bore, each of said lines of contacts being parallel to the striker, and means on the support arranged adjacent the striker and adapted to coact with the inner frustum portion of each of the detents for preventing outward movement of the detents by centrifugal force as the projectile is fired from the gun until the setback force of the firing pin has decreased sufficiently to permit the firing pin to be moved forwardly by the driving force imparted by said frustum portions as the detents move outwardly to said armed position.

5. In a safety device for an explosive shell adapted to be fired from a gun, in combination, a nose secured to said shell and having a centrally disposed bore therein in communication with a circular well, said bore and well member and having a cythe firing" '7 b ing arranged. eoaxially with respecttotheaxis of. the shlclLlasupport secured: .tosaid nose-and disposed within said well -and,having-a',shou1der thereon adapted to en the forward wall defining the well,.-a bearing memheron, said support and in abutting engagement with the wall definingsaid bore, and having a cylindrical bearing surface. centrally disposed therein, a firing 'pin, a stop member on said firingpin and. slidably arranged within said bearing, surface, a striker formed. on oneend of said stopmember, an impact mernher secured tothe other end (lithe stop-member and. adapted, to drive the striker into firing engagement with said explosive shell upon impact of. the shell. with a targeL-saidstriker having a cylindrical portion thereon, said support having a transverse cylindrical opening extendingtherethrough with the axis thereof gintersecting the axis of thelstriker, a pair of detents respectively. arranged Within said opening on opposite sides of .said= striker and'adapted totbe tilted within the opening andinoved from a an initialsafe positionto an armed position by centrifugal force as the shell travels along a trajectory, each. of said detents having a pair-of. abutting frustumportions adapted to impart a driving force to the firing pin as the detents move from said safe position to :said armed position and a pair of cylindrical portions respectively. intersecting the basis of thefrustum portions andsa pair -of.conica1 surfaces respectively arranged on the end portions thereof in intersecting relation with the cylindrical portions, an annular resilient member arranged withinsaid .vvell andadapted tourge the detents yieldahlvagainst: the. striker .hvpressure applied .fl1ereby,-.theconical. surfaceson; the ends of; each-oi the detents. being; adapted to applysaid pressure. along :a. line of contact .be-. tween the detent and resilient. membertand a' second ReferencesCited in the file of thispatent UNITED STATES PATENTS 1,131,164 'Semple Mar. '9, .1915 1,288,889 Hines. .Dec. 24, 191 s I v "FOREIGN PATENTS 145,829 Great Britain June 28, 1920 835,304 France Dec. 1-9, .1938 I 504,944 Great Britain, May 2, 1939 516,035 Great Britain Dec. 20, 1939 886,912 ;.France July 19, 1943 

1. A SAFETY DEVICE FOR PROJECTILE ADAPTED TO BE FIRED FROM A GUN AND HAVING AN EXPLOSIVE CHARGE THEREIN, MEANS INCLUDING A FIRING PIN SLIDABLY AND COAXIALLY ARRANGED WITHIN SAID PROJECTILE AND HAVING A STOP MEMBER THEREON, A STRIKER ON THE FIRING PIN ADJACENT SAID STOP MEMBER AND ADAPTED TO FIRE SAID EXPLOSIVE CHARGE, SAID STRIKER HAVING A CYLINDRICAL PORTION THEREON, A CYLINDRICAL BORE DISPOSED WITHIN THE PROJECTILE WITH THE AXIS THEREOF INTERSECTING THE AXIS OF THE STRIKER, A PAIR OF DETENTS RESPECTIVELY ARRANGED WITHIN SAID BORE ON OPPOSITE SIDES OF SAID STRIKER AND ADAPTED TO BE TILTED WITHIN THE BORE AND MOVED FROM AN INITIAL SAFE POSITION TO AN ARMED POSITION BY CENTRIFUGAL FORCE DURING THE TRAVEL OF THE PROJECTILE ALONG A TRAJECTORY, EACH OF SAID DETENTS HAVING A PAIR OF ABUTTING FRUSTUM PORTIONS ADAPTED TO IMPART A DRIVING FORCE TO THE FIRING PIN AS THE DETENTS MOVE FROM SAID SAFE POSITION TO SAID ARMED POSITION AND A PAIR OF CYLINDRICAL PORTIONS RESPECTIVELY INTERSECTING THE BASES OF THE FRUSTUM PORTIONS AND A PAIR OF CONICAL SURFACES RESPECTIVELY ARRANGED ON THE END PORTIONS THEREOF IN INTERSECTING RELATION WITH THE CYLINDRICAL PORTIONS, MEANS FORMING A CIRCULAR CHAMBER WITHIN THE PROJECTILE IN COMMUNICATION WITH THE OUTER END OF SAID BORE AND HAVING THE AXIS THEREOF IN ALIGNMENT WITH SAID STRIKER A SUBSTANTIALLY CYLINDRICAL RESILIENT MEMBER DISPOSED WITHIN SAID CHAMBER AND ADAPTED TO URGE THE DETENTS YIELDABLY AGAINST THE STRIKER BY PRESSURE APPLIED THEREBY, THE CONICAL SURFACES ON THE ENDS OF THE DETENTS BEING SO PROPORTIONED AS TO APPLY SAID PRESSURE ALONG A LINE OF CONTACT BETWEEN EACH OF THE DETENTS AND THE RESILIENT MEMBER AND A SECOND LINE OF CONTACT BETWEEN EACH OF THE DETENTS AND THE CYLINDRICAL PORTION OF THE STRIKER WHEN THE DETENTS ARE TILTED WITHIN SAID BORE, EACH OF SAID LINES OF CONTACTS BEING PARALLEL TO THE STRIKER, ND MEANS ON THE PROJECTILE ARRANGED ADJACENT THE STRIKER AND ADAPTED TO COACT WITH THE INNER FRUSTUM PORTIONS OF THE DETENTS FOR PREVENTING OUTWARD MOVEMENT OF THE DETENTS BY CENTRIFUGAL FORCE AS THE PROJECTILE IS FIRED FROM THE GUN UNTIL THE SETBACK FORCE OF THE FIRING PIN HAS DECREASED SUFFICIENTLY TO PERMIT THE FIRING PIN TO BE MOVED FORWARDLY BY THE DRIVING FORCE IMPARTED THERETO BY SAID FRUSTUM PORTIONS AS THE DETENTS MOVE OUTWARDLY TO SAID ARMED POSITION. 